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A hydrophobic composite coating was obtained on the carbon steel surface through electrochemical deposition of a copper coating in a sulfate solution and chemical vapor deposition of a carbon fiber film. It alleviated the serious corrosion problem of carbon steel on the evaporator of hot film coupled seawater desalination system in harsh marine environment. The morphologies and compositions of the coatings were analyzed, revealing the influence of electrodeposition time on their performance. The micro-nano copper structure formed by electrodeposition significantly improved the deposition effect of carbon layer. Additionally, experiments with seawater solution contact angle tests indicated that electrodeposition transformed the surface properties from hydrophilic to hydrophobic, effectively inhibiting the diffusion of corrosive medium into the interior of the substrate. Through polarization curves, electrochemical impedance spectroscopy, and other analyses, it was demonstrated that the hydrophobic coating significantly improves the corrosion resistance of carbon steel substrates in seawater environments, surpassing the performance of traditional duplex steel.

Surface roughness is an important factor that affects the wetting of molten metal on ceramics. The effect of surface roughness of the alumina substrate on the contact angle, contact diameter, drop height and surface tension of molten lead was investigated in the temperature range of 923–1123 K. The microstructure of the lead/substrate interface was observed by SEM. The surface free energy of alumina substrates was calculated by the geometrical average method. When the surface roughness of the substrate increased from 0.092 to 2.23 μm, the surface free energy increased gradually, ranging from 13.356 to 39.998 mJ/m2. The contact diameter of lead droplets decreased from 9.111 to 7.19 mm. The lead drop height increased from 3.41 to 3.85 mm. The contact angle increased from 113.05° to 137.15°. Moreover, the surface depression of the alumina substrate was filled with lead, and no obvious change was observed. The results demonstrated that the wetting of lead drop on alumina substrates was consistent with the Wenzel state.

Slag movement on SiO2-based prism refractories in different slag systems was observed. The cross section shape evolution mechanism was discussed. Two types of shape evolution appear. For PbO−SiO2slag whose surface tension improves with SiO2concentration, slag film flows up along four edges under axial Marangoni shear force and wettability. Then, it flows down along four lateral faces under gravity. Corrosion rate at edges is larger than that on lateral faces due to different SiO2solubilities of ascending and descending flow. Prism cross section shape changes from square to round. For FetO−SiO2slag whose surface tension reduces with the increase of SiO2concentration, slag film flows up under the inflence of wettability. Then, it flows down under Marangoni shear force and gravity. Compared to four edges, slag is mainly up and down on four lateral faces due to larger surface tension and size. So, prism cross section shape keeps square.

In order to study the flexural behavior of steel fiber reinforced concrete (SFRC) shield tunnel segment, two full scale shield tunnel segments and twelve reduced scale shield tunnel segments were made and tested. Based on the experiment study, the effectiveness of reduced scale segment was analyzed. Meanwhile, based on the fail mode, load-deflection curves and crack width, the part substitution of steel reinforcement by steel fibers was studied. Test results showed that the reduced scale model can reflect the flexural behavior of full scales tunnel segment and 45kg/m3 steel fibers of 3D type can replace 17% longitudinal reinforcement and 70% stirrups.

Ceramsite cellular concrete (CCC for short) is a kind of lightweight aggregate concrete. In this paper, the selection of materials and design of mix proportion have been discussed, and basic property tests has been done. The compressive strength was proved up to the National Standards of P. R. GB50003-2001(code for design of masonry structures), furthermore, elastic modulus and Poisson's ratio were also introduced. Questions remain regarding the quality control of the product, and further work is needed to resolve this contradiction.

Ceramisite cellular concrete is a kind of energy-saving materials, which has many advantages, such as low self-weight, better insulation and so on. This paper describes an experimental study of hydration heat process .It proved that the ambient temperature, the amount of fly ash and silica fume influence hydration speed apparently and compressive strength of the concrete.

The aim of present work is to further investigate the flexural behavior of FRC with four types of hooked end steel fibers. The flexural toughness of FRC beams was tested under a three point bending system, and the data of experiments were analyzed according to the standard JGJ/T221-2010 and RILEM recommendation. The results showed equal dosage of different aspect ratio fibers didn’t result in the same flexural toughness. It was found that nominal ultimate flexural strength () and equivalent flexural strength () of beams increased as aspect ratio of the steel fiber was increased. However, the highest equivalent flexural strength () was obtained by the fiber with aspect ratio of 67.

On the basis of traditional static finite element simulation, the paper adopts time spectral element method with higher accurate of interpolation precision to disperse the alternating mechanical load, meanwhile, applies the load results to its piston dynamic analysis to get the time history curve of piston stress and distortion. What we get from the experiment provides theoretical foundation for further study of piston fatigue analysis and life prediction.

A series of experiments have been undertaken to investigate the effects, on compressive strength, of variable sand/cement ratios and cement grade. Ten mixtures of different s/c ratios used two kinds of cement were cast and the compressive strength at different curing ages was tested. The results indicate that the compressive strength gets lower as the s/c ratio increases for both 42.5R and 32.5R cement. For the mixtures used 32.5R cement, the 28-day compressive strength is pretty low for the s/c ratios of 1.5 and 2. The specimens used 42.5R cement have higher compressive strength than those with 32.5R cement. The compressive strength decreases from 42.5R to 32.5R cement are significantly smaller for the s/c ratios of 0.5 and 1 than the other three s/c ratios.

The free deformation of cellular ceramisite concrete at early-age was measured with untouched micro-displacement sensor. The results showed foam lacking stability led to shrinkage immediately after casting. Then the concrete presented expansion. After that it would shrink except thermal expansion. The change of ambient temperature led to the deformation of concrete, and a small quantity of sand had negligible effect on this type of deformation. The rate of thermal expansion was faster than that of thermal contraction.

800x600 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} The current research was implemented to study the practical unloading stress path that the slope mass experienced during the excavation process, which is very important in the stress and strain numerical analysis. Series of unloading tests were carried out under different confining pressure. During the test process, the minor principal stress was kept decreasing, while the major principal stress was kept unchanged to simulate the stress path in some locations of the soil slope, such as at the top of the slope. The corresponding conventional triaxial compression tests were also carried out as comparison. It is shown that there are many differences between the unloading and loading tests. Through analyzing, the tests results could be applied in the development of unloading constitutive models of excavation soil mass. Also, such unloading tests data are valuable in calibration and verification of the current existing popularly used models.

Most soil constitutive models were developed based on the traditional triaxial tests with isotropic assumption, in which the load is applied as the major principal stress direction and the other two principal stresses are symmetric. When such isotropic models are applied to practical analysis, stress induced anisotropy under complex stress state and the middle principal stress effects are often neglected, thus there are many disagreements between the calculated results and the infield testing data. To simulate the practical loading process, true triaxial tests were carried out on geomaterial under three-dimensional stress state. It was found that the stress induced anisotropy effects are remarkable and the middle principal stress effects are obvious because of the initial three-dimensional stress state. Such kind of stress-induced anisotropy could have important impact on the numerical analysis results and should be taken into consideration when developing the constitutive model.